jdowney
Well-known member
I've found it often pays to ask the guys who do the actual work and listen to what they say. Usually they've solved the problem repeatedly already, but the engineer simply has never seen how they did it.
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Whats the best way to secure this I beam?
- Thread starter Impala_Guy
- Start date
jdowney
Well-known member
Bolts or all thread and nuts used as a stop is a great way to fail a crane inspection. Seen that happen, the inspector didn't like that the attachment hardware - the bolt - was also the thing getting beat up when the trolley hit it. That crane was a shitshow however, it also had bolts as hinge pins so it could swing out of the way. If well done instead of quick and dirty site built, I could see these things passing ok.
A more typical method is to bolt on a piece of angle iron for a stop. Assume that people are going to ram into whatever it is at top speed now and then. They shouldn't, but it's still going to happen.
Yeah I'm working up to something like this, not sure if this is the trolly I'm going to use or not but there will be a solid mechanical stop. I will probably use a chain drive trolley rather than a manual one, that should help avoid the slam assess.
jdowney
Well-known member
Oh, yeah. That would likely pass without comment, especially if you make the plate wide enough to stop the trolley before the wheels hit the bolts. It looks engineered rather than an afterthought.
I've seen them slam chain hoists too. At both my last two jobs we get tons of fat greasy moths in the summer, they crawl in every small space they can find. I've seen people slam the cranes into stops repeatedly to shake the moths out before lifting optics that we don't want covered in moth piss (the do that when startled into flying).
We’re talking 500 pounds…
Yeah when in doubt keeping things simple and stick to "if it looks right, it probably works right" can be your friend. This nice chain hoist has built in stops and looks like there is no discconect on the drive so it should cut down on the slam asses.Here is a picture of a commercially available I-Beam trolley system This capacity is 3K lbs. If you beef up the supports you could possibly get a higher load capacity.
View attachment 337517
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All finished, the 16x 3/4" bolts on the 4 feet securing them to the skid can be full torque, all the others will use nylock nuts and washers both sides and in the work instructions I'll note to torque them 50 - 75 ft lbs checking for deformation. The 3in collars around the lift rated eyebolts holding the beam clamps keep the beam assy from swinging / tilting as the 600lb DC motors are moved out to the aisle where they can be lowered onto a die cart.
If you, tdb59 and tommygun have a better idea for a cost effective (I've got to use union labor), bolt together assembly that can be palleted and loaded on a Conestoga semi trailer with a couple other heavy equipment skids, and be brought in through a 6' x 8' door, I'm open to suggestions since you chose to belittle me.
Good point, I have a forklift jib at our shop that can handle a Cat truck engine at 5' with our 9,000 Lb. Hyster. 500# at ten feet would be bunny piss.
That's what I was thinking too or one on wheels like an engine hoist and forget what they are called. I see his setup more on filter vessels say 36" diameter to move the lid out of the way. Generally speaking, the davits tend to freeze up after being in the weather for years. If the beam doesn't extend beyond the structure, I'm not sure I understand the purpose. Been out of the maintenance game almost 20 years so just curious.
No belittling, just noticing that this forum is getting questions about engineering a portable lifting device.
A device that has to move a load overhead of critical equipment without any racking in the process.
Not shown is any anchoring to prevent end lifting or sliding when the load is conveyed.
( my mistake. I overlooked this posted by the OP )
If the total weight of the lifting frame is
less than 4x of the load, this is a potential oops.
If the lifting frame is not dead nuts level, inertia will bite.
Potential shear of fasteners is down the list, but it is there.
It may work just dandy fine.
Insufficient budget relative to potential damage and downtime would be my concern, if I was taking it on.
Which obviously, I am not.
At least cutting a check to an experienced mechanical engineer for his drawings and consulting fee rather than asking for free specs here
may be wise.
I do wish you success.
A device that has to move a load overhead of critical equipment without any racking in the process.
( my mistake. I overlooked this posted by the OP )
less than 4x of the load, this is a potential oops.
If the lifting frame is not dead nuts level, inertia will bite.
Potential shear of fasteners is down the list, but it is there.
It may work just dandy fine.
Insufficient budget relative to potential damage and downtime would be my concern, if I was taking it on.
Which obviously, I am not.
At least cutting a check to an experienced mechanical engineer for his drawings and consulting fee rather than asking for free specs here
may be wise.
I do wish you success.
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If you tighten a grade 8 3/4 - 10 you have 33,000 lbf., not 500. Same mistake caused the collapse of a walkway in Kansas City in 1981 that killed over a hundred people.We’re talking 500 pounds…
Here is a box beam where the bolt pulled through.
Okay.
I had overlooked this from the OP-
"its anchored to the corners of a 5 ton skid with 3/4" bolts, 4 per foot."
................
I'm just looking at it from the standpoint if I am the one operating it. I can lift the motor out of the way to work on the pump. But what do I do if I need to take the motor out? I was an electrician. I'd tell the mechanic boys back in the day that the wires and shit are disconnected. It's your baby now and don't drop it and call me when you guys want me to reconnect it and make it spin after you bring it back from the electrical shop
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In this case only the bolts securing the posts to the skids will be torqued to SAE specs, there is no need for that kind of clamping force on the rest of the gantry. The nylock nuts on the upper members do not need to be torqued to 300 ft lbs to stay in place so I'm not sure why you are stuck on this. I may add two more bolts in each of the four corner braces, and maybe some diagonals on the back of the frame though I think the latter may be overkill.
Gazz
Well-known member
I look at your drawing and wonder why the trolley I-beam is hanging from two bolts with those pipe spacers and not suspended directly from the two end square tubes. Seems that you are adding something that doesn't need to be there but I don't know about other requirements. Short chain on your hoist? Four pieces of off the shelf truck spring shackles and some plates would mean you wouldn't have to drill the tube. I also wondered about what you were going to do with them once hoisted but the fork truck comment answered that question.
Actually I didnt ask your opinions on how to design the gantry, just how to level out the nuts on the I beam which is something I've never dealt with before, and for which there was a simple answer that another poster provided. And I am an experienced mechanical engineer with a degree and 25 years on the job. I'm not a structural engineer but I know enough that unless they get drunk and start swinging the motor from side to side that its not going to bring this thing down to the ground. I may put some 6in channel diagonals in there though since you all think I'm such an idiot.
I could bolt it directly using the beam nuts mentioned but my thought was that it might be easier to assemble if the clamps were hung first and then the beam lifted upto the clamps. Holding a 200+ lb beam in the air and trying to line up 8 bolt holes seems tough. The clevises on the clamps are rated for 5000lbs each.
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For SAE grade 8 the dry torque for a 3/4 UNC bolt is around that. Its just not needed in this case since tensile loads on the bolts are low and Im using nuts with nylon locking collars.
3/4" Cat headbolts torque to 330 LB. FT. all 26 of them... twice. I like to get the drivers to do the pulling.
Gravity, you can trust it was what I learned from most mechanical engineers.
Understand, hence my comment as to why start getting into deformation mode on the surfaces when it's already overkill. Load on each bolt is maybe 150 until it heads to one side. I'm too old to do the trig.
Yeah but that's different. I was thinking to myself this morning as to those dudes doing hot rivets on skyscrapers a hundred years ago and was going to suggest that till I realized that there was not enough room to swing a maul after looking at CAD3/4" Cat headbolts torque to 330 LB. FT. all 26 of them... twice. I like to get the drivers to do the pulling.
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I don't think you read the exchange properly.